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SubjectRe: [PATCH v6 6/9] input: touchscreen: resistive-adc-touch: add generic resistive ADC touchscreen
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On 22.05.2018 00:06, Dmitry Torokhov wrote:
> On Mon, May 21, 2018 at 01:27:54PM +0300, Eugen Hristev wrote:
>> This adds a generic resistive touchscreen (GRTS) driver, which is based
>> on an IIO device (an ADC). It must be connected to the channels of an ADC
>> to receive touch data. Then it will feed the data into the input subsystem
>> where it registers an input device.
>> It uses an IIO callback buffer to register to the IIO device
>>
>> Some parts of this patch are based on initial original work by
>> Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy
>>
>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>
> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> I assume this will go through IIO tree? Just a couple of comsmetic
> comments below, feel free to ignore.

Thank you, I modified as you suggested and sent out v7. Jonathan said in
an earlier e-mail that he will take them through IIO tree. Waiting on
his feedback.

Eugen
>
>> ---
>> Changes in v6:
>> - changed a dev_err to dev_dbg which was forgotten in v5.
>>
>> Changes in v5:
>> - return error on probe if failed add_action_or_reset
>> - renamed property touchscreen-threshold-pressure to
>> touchscreen-min-pressure, changed variables accordingly
>>
>> Changes in v4:
>> - added a small description in file header
>> - changed MAX_POS_MASK to GRTS_MAX_POS_MASK
>> - initialized press with 0, as this value means no touch.
>> press has to be initialized because compiler/checkpatch complains
>> that can be used uninitialized.
>> - changed of_property_read_u32 to device_*
>> - set_abs_params for pressure will have range according to threshold
>> - changed evbit and keybit with set_capability call
>> - changed variable names to error instead of ret
>> - checked errors for add_action_or_reset
>> - cosmetic cleaning
>>
>> Changes in v3:
>> - pressure now reported naturally growing down-up
>> - using helpers from touchscreen.h to parse DT properties
>> - added devm_add_action_or_reset to handle callback buffer clean on exit
>> - changed compatible and threshold property to adapt to changed bindings
>>
>> Changes in v2:
>> - this is now a generic resistive adc touchscreen driver
>>
>>
>> drivers/input/touchscreen/Kconfig | 13 ++
>> drivers/input/touchscreen/Makefile | 1 +
>> drivers/input/touchscreen/resistive-adc-touch.c | 201 ++++++++++++++++++++++++
>> 3 files changed, 215 insertions(+)
>> create mode 100644 drivers/input/touchscreen/resistive-adc-touch.c
>>
>> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
>> index 4f15496..8f85d3a 100644
>> --- a/drivers/input/touchscreen/Kconfig
>> +++ b/drivers/input/touchscreen/Kconfig
>> @@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI
>> To compile this driver as a module, choose M here: the
>> module will be called ad7879-spi.
>>
>> +config TOUCHSCREEN_ADC
>> + tristate "Generic ADC based resistive touchscreen"
>> + depends on IIO
>> + select IIO_BUFFER_CB
>> + help
>> + Say Y here if you want to use the generic ADC
>> + resistive touchscreen driver.
>> +
>> + If unsure, say N (but it's safe to say "Y").
>> +
>> + To compile this driver as a module, choose M here: the
>> + module will be called resistive-adc-touch.ko.
>> +
>> config TOUCHSCREEN_AR1021_I2C
>> tristate "Microchip AR1020/1021 i2c touchscreen"
>> depends on I2C && OF
>> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
>> index dddae79..843c7f9 100644
>> --- a/drivers/input/touchscreen/Makefile
>> +++ b/drivers/input/touchscreen/Makefile
>> @@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877) += ad7877.o
>> obj-$(CONFIG_TOUCHSCREEN_AD7879) += ad7879.o
>> obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o
>> obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o
>> +obj-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o
>> obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o
>> obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o
>> obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o
>> diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
>> new file mode 100644
>> index 0000000..05d629b
>> --- /dev/null
>> +++ b/drivers/input/touchscreen/resistive-adc-touch.c
>> @@ -0,0 +1,201 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * ADC generic resistive touchscreen (GRTS)
>> + * This is a generic input driver that connects to an ADC
>> + * given the channels in device tree, and reports events to the input
>> + * subsystem.
>> + *
>> + * Copyright (C) 2017,2018 Microchip Technology,
>> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
>> + *
>> + */
>> +#include <linux/input.h>
>> +#include <linux/input/touchscreen.h>
>> +#include <linux/iio/consumer.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define DRIVER_NAME "resistive-adc-touch"
>> +#define GRTS_DEFAULT_PRESSURE_MIN 50000
>> +#define GRTS_MAX_POS_MASK GENMASK(11, 0)
>> +
>> +/**
>> + * grts_state - generic resistive touch screen information struct
>> + * @pressure_min: number representing the minimum for the pressure
>> + * @pressure: are we getting pressure info or not
>> + * @iio_chans: list of channels acquired
>> + * @iio_cb: iio_callback buffer for the data
>> + * @input: the input device structure that we register
>> + * @prop: touchscreen properties struct
>> + */
>> +struct grts_state {
>> + u32 pressure_min;
>> + bool pressure;
>> + struct iio_channel *iio_chans;
>> + struct iio_cb_buffer *iio_cb;
>> + struct input_dev *input;
>> + struct touchscreen_properties prop;
>> +};
>> +
>> +static int grts_cb(const void *data, void *private)
>> +{
>> + const u16 *touch_info = data;
>> + struct grts_state *st = private;
>> + unsigned int x, y, press = 0x0;
>> +
>> + /* channel data coming in buffer in the order below */
>> + x = touch_info[0];
>> + y = touch_info[1];
>> + if (st->pressure)
>> + press = touch_info[2];
>> +
>> + if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
>> + /* report end of touch */
>> + input_report_key(st->input, BTN_TOUCH, 0);
>> + input_sync(st->input);
>> + return 0;
>> + }
>> +
>> + /* report proper touch to subsystem*/
>> + touchscreen_report_pos(st->input, &st->prop, x, y, false);
>> + if (st->pressure)
>> + input_report_abs(st->input, ABS_PRESSURE, press);
>> + input_report_key(st->input, BTN_TOUCH, 1);
>> + input_sync(st->input);
>> +
>> + return 0;
>> +}
>> +
>> +static int grts_open(struct input_dev *dev)
>> +{
>> + int error;
>> + struct grts_state *st = input_get_drvdata(dev);
>> +
>> + error = iio_channel_start_all_cb(st->iio_cb);
>> + if (error) {
>> + dev_err(dev->dev.parent, "failed to start callback buffer.\n");
>> + return error;
>> + }
>> + return 0;
>> +}
>> +
>> +static void grts_close(struct input_dev *dev)
>> +{
>> + struct grts_state *st = input_get_drvdata(dev);
>> +
>> + iio_channel_stop_all_cb(st->iio_cb);
>> +}
>> +
>> +static void grts_disable(void *data)
>> +{
>> + iio_channel_release_all_cb(data);
>> +}
>> +
>> +static int grts_probe(struct platform_device *pdev)
>> +{
>> + struct grts_state *st;
>> + struct input_dev *input;
>> + struct device *dev = &pdev->dev;
>> + struct iio_channel *chan;
>> + int error;
>> +
>> + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
>> + if (!st)
>> + return -ENOMEM;
>> +
>> + error = device_property_read_u32(dev, "touchscreen-min-pressure",
>> + &st->pressure_min);
>> + if (error) {
>> + dev_dbg(dev, "can't get touchscreen-min-pressure property.\n");
>> + st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN;
>> + }
>
> I do not think it makes sense to complain about missing property if
> there is no "pressure" channel. Probably move down?
>
>> +
>> + /* get the channels from IIO device */
>> + st->iio_chans = devm_iio_channel_get_all(dev);
>> + if (IS_ERR(st->iio_chans)) {
>> + if (PTR_ERR(st->iio_chans) != -EPROBE_DEFER)
>> + dev_err(dev, "can't get iio channels.\n");
>> + return PTR_ERR(st->iio_chans);
>
> error = PTR_ERR(st->iio_chans);
> if (error != -EPROBE_DEFER)
> dev_err(dev, "can't get iio channels.\n");
> return error;
>
>> + }
>> +
>> + chan = &st->iio_chans[0];
>> + st->pressure = false;
>> + while (chan && chan->indio_dev) {
>> + if (!strcmp(chan->channel->datasheet_name, "pressure"))
>> + st->pressure = true;
>> + chan++;
>> + }
>> +
>> + input = devm_input_allocate_device(dev);
>> + if (!input) {
>> + dev_err(dev, "failed to allocate input device.\n");
>> + return -ENOMEM;
>> + }
>> +
>> + input->name = DRIVER_NAME;
>> + input->id.bustype = BUS_HOST;
>> + input->open = grts_open;
>> + input->close = grts_close;
>> +
>> + input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
>> + input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
>> + if (st->pressure)
>> + input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
>> + 0xffff, 0, 0);
>> +
>> + input_set_capability(input, EV_KEY, BTN_TOUCH);
>> +
>> + /* parse optional device tree properties */
>> + touchscreen_parse_properties(input, false, &st->prop);
>> +
>> + st->input = input;
>> + input_set_drvdata(input, st);
>> +
>> + error = input_register_device(input);
>> + if (error) {
>> + dev_err(dev, "failed to register input device.");
>> + return error;
>> + }
>> +
>> + st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st);
>> + if (IS_ERR(st->iio_cb)) {
>> + dev_err(dev, "failed to allocate callback buffer.\n");
>> + error = PTR_ERR(st->iio_cb);
>> + return error;
>
> Simply:
>
> return PTR_ERR(st->iio_cb);
>
> since you opted out of printing error codes in error messages.
>
>> + }
>> +
>> + error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
>> + if (error) {
>> + dev_err(dev, "failed to add disable action.\n");
>> + return error;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id grts_of_match[] = {
>> + {
>> + .compatible = "resistive-adc-touch",
>> + }, {
>> + /* sentinel */
>> + },
>> +};
>> +
>> +MODULE_DEVICE_TABLE(of, grts_of_match);
>> +
>> +static struct platform_driver grts_driver = {
>> + .probe = grts_probe,
>> + .driver = {
>> + .name = DRIVER_NAME,
>> + .of_match_table = of_match_ptr(grts_of_match),
>> + },
>> +};
>> +
>> +module_platform_driver(grts_driver);
>> +
>> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
>> +MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.7.4
>>
>
> Thanks.
>

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